The present invention relates to an image scanning apparatus, such as a scanner, for scanning an image on an original document by directing light from a light source onto the original document, passing reflected light from the document through an optical system, such as mirrors and so on, and allowing the document image to be captured by three CCD line sensors of R (red), G (green) and B (blue).
In recent years, image scanning apparatuses, such as scanners, for scanning an image on an original document by directing light from a light source onto the original document, passing reflected light from the document through an optical system, such as mirrors and so on, and allowing the document image to be captured by three CCD line sensors of R (red), G (green) and B (blue) have been put into practical use.
In this case, light from the light source is directed onto the original document image and the reflected light from the original document image is led to the CCD line sensors through multiple mirrors.
In such scanners, it is required to adjust the optical axes at apparatus assembly time or when, as a result of reading a half-tone image, irregularities in density and color occur over the entire surface of the read image.
For example, when density differences occur on leading and trailing edge sides of the read image or density differences occur on front and rear sides in the main scan direction, the optical axis of light from the light source directed onto each CCD line sensor is adjusted.
The optical axes to the CCD line sensors are adjusted by changing (adjusting) the angles of the mirrors used to lead reflected light to the CCD line sensors.
At the time of optical axis adjustment, an optical axis adjustment jig having a white line in the main scan direction is placed above the light source, an oscilloscope for displaying signals (voltage signals) from the CCD line sensors is connected to signal output lines of the CCD line sensors, and a dedicated control panel is connected to a CPU bus.
Using the oscilloscope, the deviation of the output of each of the CCD line sensors (red/green/blue) is corrected. The signal (voltage signal) of each CCD line sensor can be taken in only from the front of AMP. For this reason, the output signal must be confirmed with a lens cover for preventing stray light, destruction of a board and dust removed and the probe of the oscilloscope attached to the output signal (voltage signal) pin of each CCD line sensor.
The voltage signals of the CCD line sensors of red, green and blue are taken into the oscilloscope prior to entering AMP to display the amount of voltage in each of the CCD line sensors. The angle of each mirror is then adjusted with a corresponding screw so that a peak voltage value appears in the CCD line sensor of green in the center of the CCD line sensors.
At this point, the scanners must be operated for each unit; thus, a dedicated control panel is needed. The adjustment is made for each scanner. The input signals to the oscilloscope are output from the CCD line sensors in the form of changes in voltage. The output signal (voltage signal) of each of the CCD line sensors (red/green/blue) is converted into HEX data in 256 levels and used as an image processing signal. Thus, the qualitative evaluation of adjustment cannot be performed because the output signal (voltage signal) of each CCD line sensor and the signal subjected to image processing (HEX data in 256 levels) differ. As a whole, even if irregularities in density are eliminated in each unit, the density varies from unit to unit because of failure in numerical management of units.
All the work is carried out manually, spending a lot of time.
In principle, the adjustments are made by a service man using an oscilloscope. Thus, the quality of images depends on the skill of service men, providing poor serviceability.
It is an object of the present invention to provide an image scanning apparatus which scans an original document image using CCD line sensors and permits the optical axis in the CCD line sensors to be adjusted without using any special equipment.
It is another object of the present invention to provide an image scanning apparatus which scans an original document image using CCD line sensors and can adjust the optical axis automatically on an apparatus basis without using any equipment, permits field adjustments and adjustments at assembly time to be made easily, and can increase the time efficiency, improve the workability, and reduce the cost.
It is still another object of the present invention to provide an image scanning apparatus which scans an original document image using CCD line sensors and can digitize the output levels of the CCD line sensors, can perform level management for each apparatus, and can suppress variations from apparatus to apparatus.
It is a further object of the present invention to provide an image scanning apparatus which scans an original document image using CCD line sensors and can grasp output values of the CCD line sensors for each color, can grasp the color levels of a read image, and can adjust the optical axis without using any special equipment.
To attain the objects there is provided an image scanning apparatus comprising: a light source for emitting light; reflecting means for reflecting an image produced by irradiating an optical axis adjust member having a white line with the light from the light source; first conversion means for converting into pixel signals each based on the density of a corresponding one of color components of the image reflected by the reflecting means; second conversion means for converting into density signals each based on the average density over every two or more pixels in a corresponding one of the pixel signals; and display means for displaying values based on the density converted by the second conversion means for every two or more pixels for each color component.
According to the present invention there is provided an image scanning apparatus comprising: a light source for emitting light; reflecting means for reflecting an image produced by irradiating an optical axis adjust member having a white line with the light from the light source; first conversion means for converting into pixel signals each based on the density of a corresponding one of color components of the image reflected by the reflecting means; second conversion means for converting into density signals each based on the average density over every two or more pixels in a corresponding one of the pixel signals converted by the first conversion means; display means for displaying values based on the density converted by the second conversion means for every two or more pixels for each color component; and adjust means for adjusting the direction of reflection by the reflecting means on the basis of the display on the display means so that an image based on the white line is positioned in the center of the first conversion means.
According to the present invention there is provided an image scanning apparatus comprising: a light source for emitting light; a mirror for reflecting an image produced by irradiating an optical axis adjust member having a white line with the light from the light source; three CCD line sensors for converting into pixel signals each based on the density of a corresponding one of color components of the image reflected by the mirror; conversion means for converting into density signals each based on the average density over every two or more pixels in a corresponding one of the pixel signals converted by the three CCD line sensors; display means for displaying values based on the density converted by the conversion means for every two or more pixels for each color component; and adjust means for adjusting the inclination and of the direction of reflection by the reflecting means on the basis of the display on the display means so that an image based on the white line is positioned in the center of and in parallel with the three CCD line sensors.